Scientists have now identified the structure of the protein complex that powers hearing in the inner ear.
For this decade-old puzzle to be solved, 60 million roundworms were needed by researchers (Caenorhabditis elegans), which use a very similar protein complex as humans do to sense touch.
Humans only have a small amount of this protein in their inner ears so we need to find another source. This was the only way that the team was able to accumulate enough protein to study.
“We spent many years optimizing our worm-growth methods and protein-isolation strategies, and had many rock bottom’ moments when we thought about giving up.” “Sarah Clark (co-first author), a biochemist from Oregon Health and Science University, Portland.
While researchers know for a while that the transmembrane channels-like protein1 (TMC1) complex plays an important role hearing, the precise makeup of the protein remains elusive.
“This is one of the last sensory systems in which the fundamental molecular machinery of the cell has been unknown.” “Eric Gouaux is a senior biochemist at OHSU and senior author.
This research, which was published in, is thanks to you. NatureNow we know that this protein complex functions as a tension sensitive ion channel, which opens and closes depending on hair movement inside the inner ear.
Researchers discovered that electron microscopy could be used to examine the protein complex. Subunits were “poised like handles”, and the complex “resembles an accordion”.
Sound waves travelling through the ear reach the eardrum, which is the Tympanic membrane. Then it travels to the inner part of the ear, where it touches the ossicles (three of the smallest bones on the body). The ossicles hit the cochlear (snail-like), which then brushes microscopic, finger-like hairs against membranes.
These stereocilia are embedded within cells that have the TMC1 complex’s ion channels that open and close with hair movement, sending electrical signals along to the auditory nerve to brain for interpretation as sound.
“The auditory neuroscience field has been waiting for these results for decades, and now that they are right here – we are ecstatic,” “Peter Barr-Gillespie from OSHU, an OSHU otolaryngologist, was not part of the study. He is a national leader for hearing research.
Researchers may be able to find treatments for hearing impairments through this discovery.
Worldwide, more than 460million people are affected by hearing loss and deafness. Research can continue to uncover the causes of hearing loss and find innovative ways to help, treat or prevent it in our community.
This paper was published in Nature.
